*: Grade and score by the intensity of immunoreactivity staining: 0 point for absent,
1 point for weak, 2 points for moderate and 3 points for strong; then grade by the
extent of tissue staining: 0 point for no positive staining cells, 1 point for positive
ratio <25%, 2 points for 25%-49%, 3 points for 50%-79% and 4 points for ≥ 80%. Finally,
multiply the two score systems: ≤3 points for negative, >3 points for positive.